Since the invention of the phase inversion technique, substantial efforts have been dedicated to improve polymeric membrane formation, aiming for better control of membrane characteristics, and optimization of membrane structure enabling the preparation of polymeric membranes with tailored properties for specific separation applications. Despite the great efforts that have been made so far in polymeric membrane formation by phase inversion, there are still significant knowledge gaps that merits special attention. In this chapter, our objective is to highlight some of these gaps identified during the edition of this book establishing future research directions.